Process of removing amorphous wax from petroleum oils



oct. 15, 1929.'A

P. M. TRAVIS PROCESS OF REMOVING AMORPHOUS WAX FROM PETROLEUM OILS Filed July 16 1927 2 Sheets-Sheet P. M. TRAVIS Oct. 15, 1929.

PROCESS OF REMOVING AMORPHOUS WAX FROM 'PETROLEUM OILS Filed my 16. 1927 2 Sheets-Sheet 2 l INVENTOR /D/arfa//vfa/f Tri/AS ATTORNEYS Patented Oct. vl5, 1929 UNITED STATES PATENT Orf-fics PIERCE MAISON TRAVIS, 'OF RIDGEWOOD, NEW JERSEYAISSIGNORTO TRAVIS PROCESS CORPORATION, OF JERSEY CITY, NEW JERSEY, A CORPORATION 01?".y DELAWARE PROCESS or nnlfovmamonrnons WAX FROM PETROLEUM OILs Application `''led I u1y` 16,

This invention relates to improvements in treating .petroleum oils and fractions thereof, i

lim1ted' capacity due to the small capacity containing amorphous paratline wax te:ffeet the removal of the Wax therefrom While` in the amorphous state.I The process of the invention is of special value and application in the treatment of petroleum oils containing vlubricating oil constituents and amorphous wax and provides a simple and economical process adapted to remove the amorphous Wax continuously without a preliminary treatment that might impair the lubricating properties of thel oil.

In refining petroleum oils for the production of high grade lubricants it is customary to distil oil the lighter fractions, such as the gasoline, kerosene, etc., with steam or at re- `duced pressure to avoid cracking of the lubricating oil constituents as cracking reduces the viscosity'of the lubricating oil constituents and materially decreases their value.v Crude Oil reduced in this manner contains amorphous wax which tends to congeal at low temperatures and its presence is therefore i objectionable in a lubricating oil because of the high pour test it gives to the oil. Itis impossible from a practical standpoint to removethe Wax while-in an amorphous state fromoils of this character in the ordinary filter press due to rapid plugging off the filtering medium. In order to convert ,the amorphous wax to a crystalline form so that it mi ht be satisfactorily removed by ilterpressing a high temperature must b employed whichr is such as to "greatly impair the lubricating properties of the oil.

,It has been customary inthe past to blend oils of this character with a diluent such as naphtha, chill the blend to an extremely low temperature and allow the naptha-oil soluv ,tion to stand for a. period of'several days to permit the waX to settle during which t1me t-he'entire body of oil must be maintained at a temperature of about 10 F. to 0 F. This treatment, known as cold settling, re-

- quires large storage capacity and an excessive amount of refrigeratlon. I Attempts have been made to eiect the sepf aration of amorphous wax from Oils of this 1927. Serial ,Nm 206.332.

characterby'centrifugal action but such op'- erations in the past have been of a very `to insure all of the Wax present passing into solution in the diluent. The mixture is then gradually *cooled in the presence of fa finely divided solid gathering medium to a temperature of about 10 F. and slowly' agitated duringfthe chilling operation. v*The naptha serves to maintain the mixture in a iiuid statey at the extremely low temperature employed and to decrease the density of the naptha oil solution. The minute particles of solid gathering medium serve as nuclei to which the Wax adheres. The density of the'mixture of the sol-id gatheringv medium and wax adhering thereto is increased b the presence of the gathering medi-um. T e chilled oil is then subjected to centrifugal pressure to effect separation of the wax and solid gathering medium from the chilled oil and the mixture of wax and solid gathering medium is mechanically dischargedv in a continuous manner from the zone of centrifugal action at one point with movement toward the axis of rotation while the solution `oi. wax free Oil and blending naptha is discharged continuously therefrom in similar manner at another point. r

The blending naptha may be subsequently separated from the wax 'free oil by distillation and recovered for further use as a diluent.

'The solid' gathering mediummay be separated from the wax mixture by heating and allowing the solidv material to settle from the"Y etV . such as a naptha distillate.

-with a mechanical stirring device 14.

from the zone of centrifugal action a light blending naptha and a relatively heavy soli-d gathering medium may be'employed to create a comparatively Wide marginbetween the `density of the solution of the oil in the blendv ing agent and that of the mixture ofthe gathering medium and adherent wax so that a lower centrifugal pressure vmay be employed to secure the separation of the wax and oil.

The process of the invention Will be further described in connection with the accom` panying drawings which illustrate in a somewhat conventional manner one form ofapparatus adapted for the practice of the-improved process of the invention, but Vit is. intended and will bei understood that this further description is for the purpose of exemplification and thatI the invention is not limitedfthereto. 'f f In the drawings:

Fig. 1 is .a somewhat diagrammatic 'representation in elevation of an arrangement of apparatus adapted for the practice of the improved process of the invention.

Fig. 2 is an eleva-tion partly in section of one form of centrifuge suitable for use in the arrangement illustrated in Fig. 1.

Fig. 1 ofthe drawings shows a storage tank 1 connected through pump 2 and line3 with a heat insulated mixing tank 4 having a heating coil 5 and stirring'device6 arranged therein. The mixing tank 4 is also provided with a valvedy inlet connection 7 l for the introduction of a diluent material Storage bin 8 is arranged so that a finely divided solid material may be .supplied therefrom to the mix ing tank 4 through connection 9 as desired. Valved draw-olf connection 10 and pump 11 are arranged to withdraw liquid from the mixing tank 4 and convey it to the insulated cooling tank 12 provided with coil 13 through ",which asuitable cooling medium may be cir` culated. Cooling tank 12 is also equipped onnections 15, 16 and 'pump 17 are arranged to supply cooled oil from the cooling tank 12 to a centrifuge 18. Valved connection 15* may advantageously be provided to withdraw oil from the upper portion of thecoolingtank 12. A stand pipe 19 is interposed in connection 16 to assist in maintaining a constant rate of .feed to the centrifuge. :Connection 20 is provided to convey the effluent liquid fromthe centrifuge to a storage tank 21. The cold clear solution discharged f-rom the centrifuge may if desired be passed in heat exchanging relations with the fresh oil supplied to the cooling tank 12 before it is vfinally discharged to the storage tank. Connection 22 is arranged to direct solid mates conveyor 23.

The centrifuge illustrated in Fig. 2 comprises a bowl 24 supported by the supportin web 25 and rotatably mounted on the shaft 26. The element 27 is keyed' to the shaft`26 andis providedl atits outer surface with extension 28, which is helicalin formy and extendsapproximatelyto the inner sur'- face of the bowl 24. The central portion of the bowl 24 is cylindrical in form tapering toward the shaft at one end. The otherend of thebowl is provided with a ring 29 extending inwardly from the peri hery of the bowl. The tapered end of the owl is con- .tinued until it approaches nearer to the vshaft 26 than the inner edge' ofthe ring 29.

The" bowl 24 is provided with a series of openings 30 aroundfits periphery at one end beyond the ring 29. The shaft 26 extends through a'gear casing 31 and may be driven directly from any suitable source of' power, for example, by a silent chain engaging the sprocket 32. The bowl 24 and the supporting web 25 are driven by a collar 33' rom the shaft 26 through a set of dilerential '.rial discharged from the centrifuge to the A,

gears in the gear casing 31 so arranged that the bowl l24 rotates in the same direction as the helix 28 but at a slightly lower speed. While both the bowl 24 andthe helix 28 rotate at high speed the differential between p them is relatively small so that any diiiculties incident to the provision and fcare of a high speed bearing Vbetween the shaft 26 and collar 33 are eliminated. 'The .direction and speed of yrotation of thehelix 28 relative to Y that of the bowl 24 is such that the helix will operate to discharge continuously at the. tapered end of the bowl any solid material which would otherwise yaccumulate therein, for examlple, the bowl may be drivenat 1000 M1200 .Y v 1250 R. P. Collecting rings 34 and 35 are provided at opposite ends of the bowl to collect the wax. free naptha-oil solution and separated solid materialas they are discharge'dfrom the. bowl. A stutli'ng box 36 is arranged .to prevent'leakage of the. material introduced through the interior of the hollow shaft 26. y y In the operation of the apparatus described and illustrated inl accordance with the improved process of the invention the oil to be P. and the helix aty 1050 to treated for the removal of amorphousI wax, Y

acter of the oil and diluent material employed. A blend comprising 40% of the oil to be treated and60% of a closely cut naptha having an end boiling point of approximately 430911 will produce satisfactory results in most cases. The naptha-oil mixture is then heated to a temperature of"about 100 F. and

thoroughly agitated. A small amount of inely divided solid material, such as diato- .maceous earth is then introduced to the mixing tank 4 from the storage bin 8 and thoroughly mixed with 4'the naptha-oil solution by the mechanical stirring device 6. The quantity of gathering medium to be employed will vary with the wax content of the oil. About 1% by weight of 200-300 mesh fullers earth will usually be suticient to eect satisfactory separation of the wax from lthe naptha-oil solution. The mixture is then chilled in the cooler 12 to a temperature of l0 ,to 0 F. by

circulating a cooling medium such as calcium chloride 'through the cooling coil 13.` During the cooling operation the mixture should be mildly agitated at intervals to secure uniform cooling and maintainthe dispersion-of the solid gathering medium throughout the solution. The cooled oil is pumped to the stand pipe 19 from which itis supplied to centrifuge 18 in a continuous manner. The mixture entering the centrifuge through the shaft 26 passes through the hollow element 27 and is discharged to the interior of the rotatingvbowl through a series ofil openings 37 Where it` is subjected to centrifugal pressure to which the mixture subjected is many times greater than the force of gravity and causes the gathering medium and adherent wax to separate from thenaptha-oil solution forming an outer layer which is mechanically conveyed to the tapered end of the bowl by the helix 28 where it is discharged from the bowl continuously.' The motion of the helix relative to the' bowl is not sufficient to act ositively on thel liquid, due to its greater uidity, so that the inner layer of cold clear liquid will flow through the bowl axially in a direction opposite tothe motion of the outer'layer of solid material, passing over the inner edge of the ring 29 as it is displaced by fresh oil supplied to the bowl. As the gathering medium and adhered wax is mechanically conj veyed by=y the helix 28 to a point nearer the axis of rotation while still subjected to the action of centrifugal forcel than the point at which the naptha-oil solution is discharged, the last traces of the oil or solution may be separated therefrom so that a maximum yield of wax `free oil and a higher melting point wax may be obtained. The speed at which the bowl may most advantageously be drivenvvill vvary somewhat with the character of the oil, the rate at which the oil is introduced thereto, the length of the bowl ameter and 30 long a rotative speed of 1000 R. P. M. will in most cases be sufficient to effeet satisfactory separation of the gathering 'medium and adherent wax from a naptha-oil solution continuously supplied thereto at a rate 'of 3000 to 4000 gallons per hour.

Where a refinery has a lant equippedfor the old gravity method oi) cold settling, the process of the invention may be employed in yconjunction therewith; F or example, the cooled solution may be allowed to stand for a time before vcentrifuging to 4effect a preliminary concentration of the' gathering medium and adherent Wax by settling. A layer of cool clear solution may thenbe drawn olf from the upper part of the settled liquid body and the remainder of the solution containing I the wax and solid materiall concentrated therein centrifugally treated as ,above dey tling methods the variousoils or solutions now subjected to the cold settling method of treating may be treated continuously in accordance with the present invention while avoiding heavy investment in cold settling tanks and excessive refrigerating capacity. The process of the invention has the further advantages that the apparatus required `is of rugged construction and does not require critical adjustment or the supervision of a skilled operator. i

I claim: j

1. The improvement in-the treatment of petroleum oils for the removal ofamorphous Wax contained therein, comprising Vchilling the oil to be treated in the presence of a finely divided solid material and a low boiling ydiluent and subjecting the chilled mixture to centrifugal force whereby the wax andiinely i "Wax contained therein, comprising chilling the oil-to be treated in the presence of a finely divided solid material and subjecting the chilled mixture. to centrifugal force whereby the Wax and admixed finely divided solid material and the wax free oil are Separated into layers, continuously discharging the wax and admlxed solid material .from the zone IST) -in which it is subjected to centritugal force I at one point with movement towardthe axis j 3. The improvement in the treatment of petroleum oils for the removal of amorphous y'wax contained therein, comprising chilling the oil to betreated in the presence of a inely divided solid material and a low boiling naptha and subjecting the chilled mixture to centrifugal force whereby the wax and finely divided solid material and the'wax free oil and naptha are separated into layers, continuously discharginnr the wax and admixed solid material from the zone in which it is subjected to centrifugal force atone point with movement toward the axis of rotation, and continuously discharging the wax free oil and naptha from said zone with movement toward the axis of rotation at another point..

4. The improvement in the treatment of petroleum oils for the removal of amorphous wax f contained therein, comprising chilling the oil to be treated inthe presence of a finely divided solid" material and subjecting the chilled mixture to lcentrifugal forcewhereby the wax and admixed nely divided solid material and the wax free oil are separated int-o. layers, causing the wax and admixed solid material to move axially lin the zone in whichl they are subjected to centrifugal force and causing the wax free oil to move axially in said zone in the opposite direction, continuously discharging the wax and admixed solid material from vthe zone in which it is subjected to centrifugal force at one point with movement toward the axis of rotation, and continuouslyI discharging the wax free oil from said zone with movement toward the axis of rotation at another point.

5. The improvement in the treatment of petroleum oils for the removal of amorphous wax contained therein, comprising heating the oil to be treated in the presence of a low boiling diluent and subsequently chilling the admixed oil and diluent in the presence of a nely divided solid material, subjecting the chilled mixture to centrifugal force whereby ythe wax and finely divided solid material and the wax free oil and diluent are separated into layers, continuously discharging the wax and admixed solid material from the zone in which it is subjected to centrifugal force at one point with movement toward the axis of rotation, and continuously discharging the wax free oil and diluent from said zone with movement toward the axis of rotation at another point.

6. The improvement in th treatment of petroleum oils for the removal of amorphous wax contained therein, comprising heating the oil to be treated in the` presence of a low boiling naptha distillate and subsequently' chilling the admixed oil and naptha in the presence of a linely divided solid material, subjecting the chilled mixture to centrifugal force whereby the wax and finely divided solid material andthe wax free oil and naptha are separated into layers, continuously discharging the wax and admixed solid material v from the zone in= which it is subjected to centrifugal force atone point with movement toward the axis of rotation, and continuously discharging the wax free oil and naptha from said zone with movement toward the axis4 of rotation at another point.

7 The improvement in the treatment of petroleum oils for the removal of amorphous sequently drawing ofi' a layer of clear liquid.

from the upper portion of said body, withdrawing a concentrated mixture from the' lower portion ofsaid body and subjectin the mixture sov withdrawn to' centrifugal orce whereby the wax and finely divided solid material and the waxfree oil and diluent are separated into layers, continuously discharging the wax and admixed solid material from the zone in which it is'subjected to centrifugal force at one point with movement toward the axis of rotation, and continuously discharging the wax free oil and diluent material from said zone with movement toward the axis of rotation at another point.

In testimony whereof I afiix my signature.

PIERCE MASON TRAVIS. 

